Method of producing electroconductive substrate, electronic device and display device

ABSTRACT

A method of producing an electroconductive substrate including a base material, and an electroconductive pattern disposed on one main surface side of the base material includes: a step of forming a trench including a bottom surface to which a foundation layer is exposed, and a lateral surface which includes a surface of a trench formation layer, according to an imprint method; and a step of forming an electroconductive pattern layer by growing metal plating from the foundation layer which is exposed to the bottom surface of the trench.

This is a Divisional of application Ser. No. 16/038,711 filed Jul. 18,2018, which claims the benefit of Japanese Patent Applications No.2017-146671 filed Jul. 28, 2017. The disclosure of the priorapplications is hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a method of producing anelectroconductive substrate, an electronic device, and a display device.

BACKGROUND

There is a case where a transparent antenna provided with anelectroconductive substrate having transparency and electroconductivity,is mounted on a surface of a touch panel or a display. Currently, theelectroconductive substrate has been required to have high transparencyand electroconductivity, and high flexibility, according to an increasein the size and diversification of the touch panel and the display. Anelectroconductive substrate of the related art, for example, includes anelectroconductive pattern layer which is formed of a resin containingITO, a metal foil, or an electroconductive nanowire, and forms a finepattern, on a transparent base material.

However, ITO or the electroconductive nanowire is an expensive material.In addition, etching is general as a method of forming a fineelectroconductive pattern layer on a base material, but in the methodusing etching, steps such as an exposing step, a developing step, anetching step, and a peeling step, are necessary, and the number of stepsincreases. For such a reason, there is a limit to produce anelectroconductive substrate at low cost.

In Japanese Unexamined Patent Publication No. 2016-164694, a method isdisclosed in which a trench is formed on a transparent base materialformed of a resin, the entire surface of the transparent base materialis filled with an electroconductive material such as copper according toa vapor deposition method or a sputtering method, the electroconductivematerial except for that in the trench is removed by etching, and thus,an electroconductive layer is formed, as a method of producing theelectroconductive substrate at low cost. On the other hand, inInternational Publication No. 2014/153895, a method is disclosed inwhich a trench is formed on a transparent base material formed of aresin, and the trench is filled with an electroconductive material.

SUMMARY

However, in the electroconductive substrate of the related art,including the electroconductive pattern layer filling the trench, theelectroconductive layer is peeled off, or electroconductivity decreases,at the time of repeatedly bending the electroconductive substrate.

An object of the present invention is to provide a method capable ofproducing an electroconductive substrate, in which an electroconductivepattern layer filling a trench is provided, and the peeling of theelectroconductive pattern layer and a decrease in electroconductivitydue to bending are suppressed, and a method of producing an electronicdevice and a display device, using the electroconductive substrate.

According to one aspect of the present invention, a method of producingan electroconductive substrate including a base material, and anelectroconductive pattern layer disposed on one main surface side of thebase material, is provided.

A method of producing an electroconductive substrate according to afirst aspect, includes: a step of forming a trench including a bottomsurface to which a foundation layer is exposed, and a lateral surfacewhich includes a surface of a trench formation layer according to animprint method including pushing a mold including a convex portion intothe trench formation layer formed on the foundation layer which isformed on the base material, the foundation layer containing a catalyst;and a step of forming the electroconductive pattern layer which includesmetal plating and fills the trench, by growing the metal plating fromthe foundation layer which is exposed to the bottom surface of thetrench.

A method of producing an electroconductive substrate according to asecond aspect, includes: a step of forming a trench including a bottomsurface to which a foundation layer is exposed, and a lateral surfacewhich includes a surface of a trench formation layer according to animprint method including pushing a mold including a convex portion intothe trench formation layer formed on the foundation layer which isformed on the base material; a step of adsorbing a catalyst in thefoundation layer which is exposed to the bottom surface of the trench;and a step of forming the electroconductive pattern layer which includesmetal plating and fills the trench, by growing the metal plating fromthe foundation layer in which the catalyst is adsorbed.

In the first aspect and the second aspect, it is preferable that themetal plating is grown such that a gap is formed between at least a partof a lateral surface of the electroconductive pattern layer and thelateral surface of the trench.

The method according to the first aspect and the second aspect, mayfurther include: a step of blackening at least a part of a surface ofthe electroconductive pattern layer, including a surface on a sideopposite to the bottom surface of the trench.

The method according to the first aspect and the second aspect, mayfurther include: a step of forming a protective film covering at least apart of a surface of the trench formation layer and theelectroconductive pattern layer on a side opposite to the base material.

The electroconductive pattern layer may include a mesh-like pattern.

According to another aspect of the present invention, a method ofproducing an electronic device including an electroconductive substratewhich includes a base material, and an electroconductive pattern layerdisposed on one main surface side of the base material, and anelectronic component, is provided.

According to still another aspect of the present invention, a method ofproducing a display device including an electroconductive substratewhich includes a base material, and an electroconductive pattern layerdisposed on one main surface side of the base material, and a lightemitting element, is provided.

The method of producing the electronic device according to anotheraspect and the method of producing the display device according to stillanother aspect, include: a step of mounting the light emitting elementon the electroconductive substrate which is obtained according to themethod described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1F are sectional views schematically illustrating a methodof producing an electroconductive substrate according to a firstembodiment.

FIG. 2A is a partially enlarged view illustrating an electroconductivesubstrate according to one embodiment, and FIG. 2B is a partiallyenlarged view illustrating an example of an electroconductive substrateof the related art.

FIGS. 3A to 3F are sectional views schematically illustrating a methodof producing an electroconductive substrate according to a secondembodiment.

FIGS. 4A and 4B are sectional views schematically illustrating oneembodiment of a method of producing a display device.

FIGS. 5A to 5C are sectional views schematically illustrating anotherembodiment of the method of producing the display device.

FIGS. 6A to 6F are sectional views schematically illustrating amodification example of the method illustrated in FIGS. 5A to 5C.

FIG. 7 is a plan view schematically illustrating a main part of thedisplay device which is obtained according to the method illustrated inFIGS. 4A to 6F.

FIGS. 8A to 8D are process charts illustrating a method of producing anelectroconductive substrate of the related art.

FIG. 9 is a schematic view of a bending resistance testing machine.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described withsuitable reference to the drawings. Here, the present invention is notlimited to the following embodiments.

First Embodiment

FIGS. 1A to 1E are sectional views schematically illustrating a methodof producing an electroconductive substrate 1A according to a firstembodiment. In the method according to this embodiment, first, asillustrated in FIG. 1A, a foundation layer 3 containing a catalyst isformed on one main surface 2 a of a film-like base material 2. A step ofFIG. 1A may be a step of preparing a laminated body including the basematerial 2, and the foundation layer 3 disposed on the base material 2.

It is preferable that the base material 2 is a transparent basematerial, in particular, is a transparent resin film. The transparentresin film, for example, may be a film of polyethylene terephthalate(PET), polycarbonate (PC), polyethylene naphthalate (PEN), a cycloolefinpolymer (COP), or a polyimide (PI). Alternatively, the base material 2may be a glass substrate, an Si wafer, or the like.

The thickness of the base material 2 may be greater than or equal to 10μm, may be greater than or equal to 20 μm, or may be greater than orequal to 35 μm, and may be less than or equal to 500 μm, may be lessthan or equal to 200 μm, or may be less than or equal to 100 μm.

The foundation layer 3 contains a catalyst and a resin. The resin may bea curable resin, and examples thereof include an amino resin, a cyanateresin, an isocyanate resin, a polyimide resin, an epoxy resin, anoxetane resin, polyester, an allyl resin, a phenolic resin, abenzooxazine resin, a xylene resin, a ketone resin, a furan resin, aCOPNA resin, a silicon resin, a dicyclopentadiene resin, abenzocyclobutene resin, an episulfide resin, an ene-thiol resin, apolyazomethine resin, a polyvinyl benzyl ether compound, acenaphthylene,and a ultraviolet ray curable resin having an unsaturated double bond,or a functional group causing a polymerization reaction by anultraviolet ray, such as cyclic ether and vinyl ether, and the like.

It is preferable that the catalyst contained in the foundation layer 3is an electroless plating catalyst. The electroless plating catalyst maybe a metal selected from Pd, Cu, Ni, Co, Au, Ag, Pd, Rh, Pt, In, and Sn,and Pd is preferable. Only one type of the metal may be independentlyused, or a combination of two or more types thereof may be used, as thecatalyst. In general, the catalyst is dispersed in the resin, ascatalyst particles.

The content of the catalyst in the foundation layer 3, may be greaterthan or equal to 3 mass %, may be greater than or equal to 4 mass %, ormay be greater than or equal to 5 mass %, and may be less than or equalto 50 mass %, may be less than or equal to 40 mass %, or may be lessthan or equal to 25 mass %, on the basis of the total amount of thefoundation layer.

The thickness of the foundation layer 3, may be greater than or equal to10 nm, may be greater than or equal to 20 nm, or may be greater than orequal to 30 nm, and may be less than or equal to 500 nm, may be lessthan or equal to 300 nm, or may be less than or equal to 150 nm.

A method of forming the foundation layer 3 on the base material 2 is notparticularly limited, and for example, may be a method in which acurable resin composition for forming the foundation layer, containing acatalyst, a resin, and a solvent as necessary, is applied onto the mainsurface 2 a of the base material 2, and the coated film is dried and/orcured. The coating, for example, is performed by using a bar coater.

Subsequently, as illustrated in FIG. 1B, a trench formation layer 4 isformed on a surface 3 a of the foundation layer 3 on a side opposite tothe base material 2. A step of FIG. 1B, may be a step of preparing alaminated body 5A including the base material 2, the foundation layer 3,and the trench formation layer 4 in this order.

It is preferable that the trench formation layer 4 is a transparentresin layer. In addition, the trench formation layer 4 may be a layercontaining an uncured photocurable or thermosetting resin. Examples ofthe photocurable resin and the thermosetting resin configuring thetrench formation layer 4, include an acrylic resin, an amino resin, acyanate resin, an isocyanate resin, a polyimide resin, an epoxy resin,an oxetane resin, polyester, an allyl resin, a phenolic resin, abenzooxazine resin, a xylene resin, a ketone resin, a furan resin, aCOPNA resin, a silicon resin, a dicyclopentadiene resin, abenzocyclobutene resin, an episulfide resin, an ene-thiol resin, apolyazomethine resin, a polyvinyl benzyl ether compound, acenaphthylene,and an ultraviolet ray curable resin having an unsaturated double bond,or a functional group causing a polymerization reaction by anultraviolet ray, such as cyclic ether and vinyl ether, and the like.

It is preferable that a refractive index (nd25) of the trench formationlayer 4 is less than a refractive index of the foundation layer 3, fromthe viewpoint of increasing the transparency of the electroconductivesubstrate, and for example, may be greater than or equal to 1.0, and maybe less than or equal to 1.7, may be less than or equal to 1.6, or maybe less than or equal to 1.5. The refractive index can be measured by areflecting spectrographic film thickness meter.

Subsequently, as illustrated in FIG. 1C and FIG. 1D, a trench (a grooveportion) 6 is formed according to an imprint method using a mold 7including a convex portion 7 a. In this step, the mold 7 including theconvex portion 7 a having a predetermined shape, is moved in a directionillustrated by an arrow A, and thus, is pushed into the trench formationlayer 4 (FIG. 1C). The mold 7 may be pushed until a tip end of theconvex portion 7 a reaches the foundation layer 3. In this state, in acase where the trench formation layer 4 is the layer containing theuncured photocurable or thermosetting resin, the trench formation layer4 is cured. In a case where the trench formation layer 4 is a layercontaining the photocurable resin, the trench formation layer 4 is curedby being irradiated with light such as an ultraviolet ray. After that,the mold 7 is detached, and thus, the trench 6 having a shape on whichthe shape of the convex portion 7 a of the mold 7 is reflected, isformed (FIG. 1D).

As illustrated in FIG. 1D, the trench 6 is formed of a bottom surface 6a to which the foundation layer 3 is exposed, and facing lateralsurfaces 6 b and 6 c including a surface of the trench formation layer 4surrounding the bottom surface 6 a. The trench 6 extends on thefoundation layer 3 such that a pattern corresponding to anelectroconductive pattern layer which is formed in the subsequent step,is formed. In order to expose the foundation layer 3 to the bottomsurface 6 a of the trench 6, the trench formation layer 4 remaining onthe foundation layer 3 in the trench 6 may be removed by etching such asdry etching, after the mold 7 is detached.

The mold 7 may be formed of quartz, Ni, ultraviolet ray curable liquidsilicone rubber (PDMS), and the like. The shape of the convex portion 7a of the mold 7, that is, the shape of the trench 6 to be formed by themold 7, is not particularly limited, and as illustrated in FIG. 1D, thelateral surfaces 6 b and 6 c may be inclined with respect to the bottomsurface 6 a, or the lateral surfaces 6 b and 6 c may be perpendicular tothe bottom surface 6 a, such that the width of the trench 6 is narrowedfrom a surface 4 a of the trench formation layer 4 on a side opposite tothe foundation layer 3 towards the bottom surface 6 a. The lateralsurfaces 6 b and 6 c may form a step.

In general, the width and the depth of the trench 6 are set tocorrespond to the width and the thickness of the electroconductivepattern layer which is formed in the subsequent step. Herein, the widthof the trench indicates the maximum width in a direction perpendicularto a direction in which the trench extends. A ratio of the depth of thetrench to the width of the trench, may be identical to an aspect ratioof the electroconductive pattern layer described below.

Next, as illustrated in FIG. 1E, an electroconductive pattern layer 8filling the trench 6, is formed. The electroconductive pattern layer 8may be formed by an electroless plating method of growing metal platingfrom the foundation layer 3. The electroconductive pattern layer 8 maybe a layer formed of single metal plating, or may be configured of aplurality of metal platings having different metals. For example, theelectroconductive pattern layer 8 may include a seed layer which ismetal plating formed on the foundation layer 3, and one or more uppermetal plating layers which are metal plating formed on a surface of theseed layer on a side opposite to the foundation layer 3. Theelectroconductive pattern layer 8 is the metal plating which is formedstarting from the foundation layer, and thus, high adhesiveness withrespect to the electroconductive pattern layer 8 and the foundationlayer 3, is obtained. Accordingly, if an electroconductive substrate isrepeatedly bent, the electroconductive pattern layer 8 can be preventedfrom being peeled off from the foundation layer 3, and excellentelectroconductivity can be maintained.

The metal plating as the electroconductive pattern layer 8, for example,contains at least one type of metal selected from copper, nickel,cobalt, palladium, silver, gold, platinum, and tin, and preferablycontains copper. The electroconductive pattern layer 8 may furthercontain a non-metal element such as phosphorus, within a range wheresuitable electroconductivity is maintained.

In a case where the electroconductive pattern layer 8 includes the seedlayer and the upper metal plating layer, a metal configuring the seedlayer and a metal configuring the upper metal plating layer may beidentical to each other, or may be different from each other, and forexample, the seed layer may contain nickel, and the upper metal platinglayer may contain copper. The upper metal plating layer may include acopper plating layer formed on the seed layer, and an uppermost layerformed on the copper plating layer, containing gold or palladium.

The laminated body 5A in which the trench 6 is formed, is dipped in anelectroless plating liquid containing a metal ion, and thus, the metalplating as the electroconductive pattern layer 8 can be formed startingfrom the catalyst contained in the foundation layer 3. Theelectroconductive pattern layer 8 filling the trench 6 is formed, andthus, the electroconductive substrate 1A can be obtained.

The electroless plating liquid contains the ion of the metal configuringthe electroconductive pattern layer 8. The electroless plating liquidmay further contain phosphorus, boron, iron, and the like.

The temperature of the electroless plating liquid at the time of dippingthe laminated body 5A in the electroless plating liquid, for example,may be 40° C. to 90° C. In addition, a dipping time of the electrolessplating liquid is different according to the thickness of theelectroconductive pattern layer 8, and for example, is 10 minutes to 30minutes.

The electroconductive pattern layer 8 extends on the foundation layer 3such that a pattern corresponding to the trench 6 is formed. Thethickness of the electroconductive pattern layer 8 may be substantiallycoincident with the thickness of the trench formation layer 4, and aratio of the thickness of the electroconductive pattern layer 8 to thethickness of the trench formation layer 4 may be within a range of 0.8to 1.2.

The width of the electroconductive pattern layer 8, may be greater thanor equal to 1 μm, may be greater than or equal to 10 μm, or may begreater than or equal to 20 μm, and may be less than or equal to 90 μm,may be less than or equal to 70 μm, or may be less than or equal to 30μm. Herein, the width of the electroconductive pattern layer indicatesthe maximum width in a direction perpendicular to an extending directionof the electroconductive pattern layer.

The width of the electroconductive pattern layer 8, may be greater thanor equal to 0.3 μm, may be greater than or equal to 0.5 μm, or may begreater than or equal to 1.0 μm, and may be less than or equal to 5.0μm, may be less than or equal to 4.0 μm, or may be less than or equal to3.0 μm, from the viewpoint of improving the transparency of theelectroconductive substrate.

The thickness of the electroconductive pattern layer 8, may be greaterthan or equal to 0.1 μm, may be greater than or equal to 1.0 μm, or maybe greater than or equal to 2.0 μm, and may be less than or equal to10.0 μm, may be less than or equal to 5.0 μm, or may be less than orequal to 3.0 μm. The width and the thickness of the electroconductivepattern layer 8 can be adjusted by changing the design of the mold 7,and by changing the width and the thickness of the trench 6.

An aspect ratio of the electroconductive pattern layer 8, may be greaterthan or equal to 0.1, may be greater than or equal to 0.5, or may begreater than or equal to 1.0, and may be less than or equal to 10.0, maybe less than or equal to 7.0, or may be less than or equal to 4.0. Bysetting the aspect ratio of the electroconductive pattern layer 8 to bein the range described above, it is possible to further increase theadhesiveness of the electroconductive pattern layer 8 with respect tothe foundation layer 3, and to further increase the electroconductivity.The aspect ratio of the electroconductive pattern layer indicates aratio of the thickness of the electroconductive pattern layer to thewidth of the electroconductive pattern layer (Thickness/Width).

The electroconductive pattern layer including the seed layer and theupper metal plating layer, can be formed by a method including formingthe seed layer on the foundation layer, and forming the upper metalplating layer on the seed layer. The laminated body 5A in which thetrench 6 is formed, is dipped in the electroless plating liquid forforming the seed layer, and thus, the metal plating is formed startingfrom the catalyst contained in the foundation layer 3, as the seedlayer. After that, the laminated body including the seed layer is dippedin the electroless plating liquid for forming an electroconductivelayer, and thus, the upper metal plating layer can be formed. Thecatalyst may be adsorbed in the seed layer before the upper metalplating layer is formed, and the upper metal plating layer may be formedstarting from the catalyst adsorbed in the seed layer.

The thickness of the seed layer, may be greater than or equal to 10 nm,may be greater than or equal to 30 nm, or may be greater than or equalto 50 nm, and may be less than or equal to 500 nm, may be less than orequal to 300 nm, or may be less than or equal to 100 nm.

It is preferable that the electroconductive pattern layer 8 is formedsuch that gaps, such as gaps 11 b and 11 c in FIGS. 1E and 1F, areformed between at least a part of lateral surfaces 8 b and 8 c and thelateral surfaces 6 b and/or 6 c of the trench 6, respectively.Accordingly, it is possible to more effectively suppress a damage on theelectroconductive pattern layer 8 if the electroconductive substrate 1Ais bent. It is preferable that gaps 11 b and 11 c are formed between thelateral surfaces 8 b and 8 c of the electroconductive pattern layer 8and both of the facing lateral surfaces 6 b and 6 c of the trench 6,respectively. The width of the gaps may be greater than or equal to 1nm, may be greater than or equal to 5 nm, or may be greater than orequal to 10 nm, and may be less than or equal to 150 nm, may be lessthan or equal to 125 nm, or may be less than or equal to 100 nm. Thewidth of the gaps indicates the maximum value of a distance between theelectroconductive pattern layer 8 and the trench 6, in the directionperpendicular to the extending direction of the electroconductivepattern layer 8. The metal plating is grown from the foundation layer 3,or the seed layer on the foundation layer 3, and thus, it is possible toeasily form the gaps between the electroconductive pattern layer 8 andthe lateral surfaces 6 b and 6 c of the trench.

The electroconductive pattern layer 8, for example, may include aplurality of linear portions extending along a certain direction, andmay form a mesh-like pattern.

The method of producing the electroconductive substrate of thisembodiment, may further include a step of blackening at least a part ofa surface of the electroconductive pattern layer 8, as necessary. Forexample, a surface 8 a of the electroconductive pattern layer 8 on aside opposite to the bottom surface 6 a of the trench 6 (hereinafter,also referred to as an upper surface 8 a of the electroconductivepattern layer), a surface of the electroconductive pattern layer 8 onthe bottom surface 6 a side of the trench 6, or both thereof, may beblackened. In addition, the lateral surfaces 8 b and 8 c of theelectroconductive pattern layer 8 may be blackened. Here, “blackening asurface” indicates that the surface is processed such that a normalreflectance with respect to light incident on the surface is reduced.

A method of blackening the surface of the electroconductive patternlayer 8 is not particularly limited, and examples of the method includea method of roughening the surface, and a method of covering theoriginal surface with a layer absorbing more light than the originalsurface, in other words, a layer blacker than the original surface(hereinafter, referred to as a “blackened surface”). The blackenedsurface may be black metal plating which is formed by using a platingliquid for black metal plating, or may be black metal plating which isformed by a Raydent treatment (Registered Trademark). In general, theblackened surface is disposed as the electroconductive layer configuringa part of the electroconductive pattern layer 8.

Examples of the black metal plating which is formed by the platingliquid for the black metal plating, include black nickel plating, blackchromium plating, black chromate of zinc plating, black rhodium plating,black ruthenium plating, alloy plating of tin-nickel-copper, alloyplating of tin-nickel, and substituted palladium plating.

For example, the black metal plating (for example, the black nickelplating) is formed on the foundation layer 3 as the seed layer, afterthe trench 6 is formed, and the upper metal plating layer is formed onthe seed layer, and thus, the surface of the electroconductive patternlayer 8 on the bottom surface 6 a side can be blackened. The black metalplating covering the surface 8 a is formed, after the electroconductivepattern layer 8 is formed, and thus, the surface 8 a of theelectroconductive pattern layer 8 on the side opposite to the bottomsurface 6 a can be blackened. In a case where the gap is formed betweenthe lateral surfaces 8 b and 8 c of the electroconductive pattern layer8 and the lateral surfaces 6 b and 6 c of the trench 6, there are manycases where the black metal plating covering not only the surface 8 a ofthe electroconductive pattern layer 8 on the side opposite to the bottomsurface 6 a of the trench 6, but also the lateral surfaces 8 b and 8 cof the electroconductive pattern layer 8, is formed by being dipped inthe plating liquid for the black metal plating.

The thickness of the blackened surface (a film of the black metalplating), may be greater than or equal to 10 nm, may be greater than orequal to 30 nm, or may be greater than or equal to 50 nm, and may beless than or equal to 150 nm, may be less than or equal to 125 nm, ormay be less than or equal to 100 nm.

In a case where the surface is blackened by the method of roughening thesurface, the surface is roughened such that the surface roughness Ra ispreferably greater than or equal to 15 nm. Ra is more preferably lessthan or equal to 60 nm. Ra can be measured by a scanning probemicroscope (SPM). The roughening is performed by a method of rougheningthe surface of the electroconductive pattern layer 8 according to anacid treatment or the like, a method of forming the electroconductivepattern layer 8 such that the surface of the electroconductive patternlayer 8 is roughened, or the like.

The method of producing the electroconductive substrate of thisembodiment, may further include a step of forming a protective film 12covering at least a part of a surface of the trench formation layer 4and the electroconductive pattern layer 8 on a side opposite to the basematerial 2, as necessary. The protective film, for example, may containa resin or a filler. Examples of the resin of the protective film,include an amino resin, an isocyanate resin, a silicon resin, an acrylicresin, a polycarbonate resin, a fluorine resin, and an ultraviolet raycurable resin having an unsaturated double bond, or a functional groupcausing a polymerization reaction by an ultraviolet ray, such as cyclicether and vinyl ether, and the like. Examples of the filler of theprotective film, include silicon oxide, zirconium oxide, titanium oxide,aluminum oxide, magnesium fluoride zinc oxide, antimony oxide,phosphorus doped tin oxide, antimony doped tin oxide, tin doped indiumoxide, Ag nano-colloid, and the like. For example, a resin compositionfor forming the protective film is applied to the surface of the trenchformation layer 4 and the electroconductive pattern layer 8 on the sideopposite to the base material 2, and the coated film is dried and/orcured, as necessary, and thus, the protective film can be formed. In acase where the gap is formed between the electroconductive pattern layer8 and the lateral surfaces 6 b and 6 c of the trench 6, the protectivefilm may fill the gap.

The thickness of the protective film, may be greater than or equal to 10nm, may be greater than or equal to 50 nm, or may be greater than orequal to 100 nm, and may be less than or equal to 5000 nm, may be lessthan or equal to 3000 nm, or may be less than or equal to 1000 nm.

A refractive index of the protective film, may be greater than or equalto 1.0, or may be greater than or equal to 1.3, and may be less than orequal to 1.6, or may be less than or equal to 1.5, from the viewpoint ofthe transparency of the electroconductive substrate. It is preferablethat the refractive index of the protective film is less than therefractive index of the trench formation layer 4. The refractive indexof the protective film, for example, can be adjusted by increasing anddecreasing the content of the filler.

The method according to this embodiment is excellent from the viewpointof enabling the electroconductive pattern layer having a constant widthto be easily formed. FIGS. 2A and 2B are partially enlarged viewsillustrating an example of the electroconductive substrate including theelectroconductive pattern layer forming the mesh-like pattern. In a caseof the electroconductive substrate which is formed by the methodaccording to this embodiment, as exemplified in FIG. 2A, the width ofthe electroconductive pattern layers 8 is not greatly changed even in aregion P in the vicinity of an intersection between twoelectroconductive pattern layers 8, and a constant width is easilymaintained. In contrast, in a case of a method of the related art inwhich the electroconductive pattern layer is formed by etching, asexemplified in FIG. 2B, there is a case where the width of theelectroconductive pattern layer 8′ increases in a region Q in thevicinity of an intersection between two electroconductive pattern layers8′. The fact that the width of the electroconductive pattern layer 8does not increase in the region in the vicinity of the intersection, isadvantageous from the viewpoint of increasing a total lighttransmittance, and the fact that a variation in the width of theelectroconductive pattern layer 8 is small, is advantageous from theviewpoint of decreasing a variation in the total light transmittance.

Further, in the method according to this embodiment, it is not necessaryto remove the extra electroconductive material according to etching, andthus, it is possible to reduce the number of steps.

Second Embodiment

FIGS. 3A to 3F are sectional views schematically illustrating a methodof producing an electroconductive substrate 1B according to a secondembodiment. The same reference numerals will be applied toconfigurations and portions corresponding to those of the methodaccording to the first embodiment of FIGS. 1A to 1F, and the repeateddescription thereof will be omitted.

The method according to this embodiment is different from the methodaccording to the first embodiment, in that a step of adsorbing acatalyst 10 in a foundation layer 9 which is exposed to the bottomsurface 6 a of the trench 6 (FIG. 3E) after the step of forming thetrench 6, and the metal plating as the electroconductive pattern layer 8is grown from the foundation layer 9 in which the catalyst 10 isadsorbed.

As illustrated in FIG. 3A, in general, the foundation layer 9 which isformed on the main surface 2 a of the base material 2, is a layer whichdoes not contain the catalyst, but is capable of adsorbing the catalyst.The foundation layer 9 may be formed of a resin such as polyacetylene,polyacene, polyparaphenylene, polyparaphenylene vinylene, polypyrrole,polyaniline, polythiophene, and various derivatives thereof, or thelike. The catalyst adsorbed in the foundation layer 9, can be the sameelectroless plating catalyst as that of the first embodiment. Forexample, a laminated body including the trench 6 including the bottomsurface 6 a to which the foundation layer 9 is exposed, is dipped in anaqueous solution containing the catalyst, and thus, the catalyst can beadsorbed in the foundation layer 9. The other steps are identical tothose of the first embodiment.

[Display Device]

A light emitting element is mounted on the electroconductive substrateproduced by the method described above, and thus, it is possible toproduce a display device including the electroconductive substrate andthe light emitting element. In the electroconductive substrate describedabove, the electroconductive pattern layer is prevented from beingpeeled off from the foundation layer, and thus, the display deviceincluding such an electroconductive substrate is produced to be thinlike cloth or paper, and can be used as a flexible display device(display) which is capable of being folded or rolled. Such a flexibledisplay device can be reduced in the size and the weight, and thestorability and the designability thereof can be improved.

FIGS. 4A and 4B are sectional views schematically illustrating oneembodiment of a method of producing the display device. In this method,first, as illustrated in FIG. 4A, a light emitting element 40 and theelectroconductive substrate 1A are prepared. The light emitting element40 includes a light emitting unit 41, a positive electrode 42 disposedon one main surface 41 a of the light emitting unit 41, and a negativeelectrode 43 disposed on the main surface 41 a with a space from thepositive electrode 42. Hereinafter, the positive electrode 42 and thenegative electrode 43 may be collectively referred to as electrodes 42and 43. The light emitting element 40 may be an element which is capableof emitting red light, green light, or blue light. The light emittingelement 40, for example, may be a light emitting diode (LED). In thisembodiment, the electroconductive pattern layer 8 of theelectroconductive substrate 1A, includes a plurality of linear portions81 and 82 extending along a certain direction.

The shape of the light emitting element 40 (the shape of the lightemitting unit 41) is not particularly limited, and for example, may bean approximately quadrangular shape (a rectangular shape, a squareshape, and the like). The dimension of the light emitting element 40 maybe suitably set, and in a case where the light emitting element 40 has aquadrangular shape, it is preferable that the width of the lightemitting element 40, is less than or equal to 100 μm, is less than orequal to 80 μm, is less than or equal to 60 μm, is less than or equal to30 μm, or is less than or equal to 20 μm, from the viewpoint of furtherimproving the resolution of the display device. In this case, it ispreferable that the length of the light emitting element 40, is lessthan or equal to 50 μm, is less than or equal to 40 μm, is less than orequal to 30 μm, is less than or equal to 20 μm, or is less than or equalto 10 μm. The width of the light emitting element 40, may be greaterthan or equal to 5 μm, may be greater than or equal to 10 μm, or may begreater than or equal to 20 μm. In this case, the length of the lightemitting element 40, may be greater than or equal to 5 μm, or may begreater than or equal to 10 μm. When the light emitting element 40 ismounted on the electroconductive substrate 1A in a step described below,the width of the light emitting element 40 is set as a directioncorresponding to the width of the electroconductive pattern layer 8. Thelength of the light emitting element 40 is set as a direction along theextending direction of the electroconductive pattern layer 8.

Next, as illustrated in FIG. 4B, the light emitting element 40 ismounted on the electroconductive substrate 1A. Such a step includesconnecting the electrodes 42 and 43 of the light emitting element 40 tothe electroconductive pattern layer 8 of the electroconductive substrate1A. At this time, the positive electrode 42 and the negative electrode43 of the light emitting element 40 are respectively brought intocontact with two adjacent linear portions 81 and 82 of theelectroconductive pattern layer 8, and thus, the light emitting element40 is electrically connected to the electroconductive pattern layer 8.Accordingly, it is possible to obtain a display device 50A in which thelight emitting element 40 is mounted on the electroconductive substrate1A.

FIGS. 5A to 5C are sectional views schematically illustrating anotherembodiment of the method of producing the display device. Such a methodis different from the method of the embodiment described above, in thatthe step of mounting the light emitting element 40 on theelectroconductive substrate 1A, includes forming a connection portion onthe electroconductive pattern layer 8 of the electroconductive substrate1A, and connecting the light emitting element 40 to theelectroconductive pattern layer 8 through the connection portion.

In this method, first, as illustrated in FIG. 5A and FIG. 5B, theconnection portion 44 is formed on the electroconductive pattern layer 8of the electroconductive substrate 1A. The connection portion 44 may beformed to be in contact with at least a part on the upper surface 8 a ofthe electroconductive pattern layer 8.

The connection portion 44 may be formed on the upper surface 8 a of theelectroconductive pattern layer 8 by using a fine ball formed of asolder alloy, or may be formed by printing a paste formed of a solderalloy. The connection portion 44 may be formed according to anelectroless plating method of growing the metal plating from theelectroconductive pattern layer 8. In a case where the connectionportion 44 is formed according to the electroless plating method, theconnection portion 44 may contain tin, silver, copper, bismuth, indium,and the like, or may contain an alloy of any two or more materials, as aconfiguration material. In this embodiment, it is preferable that theconnection portion 44 is formed by a fine ball or a paste, formed of asolder alloy.

The dimension of the connection portion 44 may be suitably set insofaras being a size in which the electrodes 42 and 43 of the light emittingelement 40 can be in contact with the connection portion 44. Forexample, as illustrated in FIG. 5B, the connection portion 44 may beformed such that the width thereof is identical to the width of theelectroconductive pattern layer 8. The connection portion 44 may beformed such that the width thereof is smaller than the width of theelectroconductive pattern layer 8, and a part of the upper surface 8 aof the electroconductive pattern layer 8 may be exposed.

Next, as illustrated in FIG. 5C, the electrodes 42 and 43 of the lightemitting element 40 are brought into contact with a surface 44 a of theconnection portion 44 on a side opposite to a surface in contact withthe electroconductive pattern layer 8, and thus, the light emittingelement 40 is connected to the electroconductive substrate 1A throughthe connection portion 44. At this time, the positive electrode 42 andthe negative electrode 43 of the light emitting element 40 are broughtinto contact with two adjacent connection portions 44, and thus, thelight emitting element 40 is electrically connected to theelectroconductive substrate 1A. Accordingly, it is possible to obtain adisplay device 50B in which the light emitting element 40 is mounted onthe electroconductive substrate 1A.

FIGS. 6A to 6F are sectional view schematically illustrating onemodification example of the method of producing the display device,including connecting the light emitting element 40 to theelectroconductive substrate 1A through the connection portion 44.According to this modification example, it is possible to more suitablyand easily mount the light emitting element 40 on the electroconductivesubstrate 1A, and thus, this modification example is particularlypreferably used in a case where a smaller light emitting element 40 ismounted on the electroconductive substrate 1A.

In this method, first, as illustrated in FIG. 6A and FIG. 6B, anadhesion layer 45 is formed on the electroconductive pattern layer 8 ofthe electroconductive substrate 1A. The adhesion layer 45 may be formedin at least a part of the upper surface 8 a of the electroconductivepattern layer 8. The adhesion layer 45 is formed, and thus, when aninsulating layer described below is formed on the trench formation layer4 and the electroconductive pattern layer 8, it is possible to preventthe insulating layer from being peeled off.

It is preferable that the adhesion layer 45 is formed according to theelectroless plating method of growing the metal plating from theelectroconductive pattern layer 8. It is preferable that the adhesionlayer 45 contains at least one type selected from the group consistingof nickel and a nickel alloy, as a configuration material, from theviewpoint of improving adhesiveness with respect to a UBM layerdescribed below, and the connection portion 44 and the light emittingelement 40 formed on the UBM layer. It is more preferable that theadhesion layer 45 contain at least one type selected from the groupconsisting of zinc and phosphorus, in addition to at least one typeselected from the group consisting of nickel and a nickel alloy.

It is preferable that a surface 45 a of the adhesion layer 45 on a sideopposite to a surface in contact with the electroconductive patternlayer 8 (hereinafter, also referred to as an upper surface 45 a of theadhesion layer 45) is roughened. The upper surface 45 a of the adhesionlayer 45 is roughened, and thus, the insulating layer described belowmore easily adheres to the upper surface 45 a of the adhesion layer 45according to an anchor effect.

A method of roughening the upper surface 45 a of the adhesion layer 45,is performed by a method of roughening the upper surface 45 a of theadhesion layer 45 after plating according to an acid treatment and thelike, a method of forming the adhesion layer 45 after the plating liquidis adjusted such that a surface of the adhesion layer 45 is roughened,or the like.

Surface roughness Ra of the adhesion layer 45 is preferably greater thanor equal to 0.1 μm, is more preferably greater than or equal to 0.3 μm,and is even more preferably greater than or equal to 0.5 μm, from theviewpoint of further improving the adhesiveness with respect to theinsulating layer described below. Ra is preferably less than or equal to1 μm, is more preferably less than or equal to 0.8 μm, and is even morepreferably less than or equal to 0.7 μm, from the viewpoint of ensuringthe strength of the display device. Ra can be measured by the samemeasurement method as the method described in the blackened surface.

The thickness of the adhesion layer 45 is preferably greater than orequal to 0.1 μm, is more preferably greater than or equal to 0.5 μm, andis even more preferably greater than or equal to 1.0 μm, from theviewpoint of obtaining suitable surface roughness Ra. The thickness ofthe adhesion layer 45, may be less than or equal to 2.0 μm, may be lessthan or equal to 1.8 μm, or may be less than or equal to 1.5 μm.

Subsequently, as illustrated in FIG. 6C, an insulating layer 46,covering the surface 4 a of the trench formation layer 4 on the sideopposite to the foundation layer 3, and including an opening portion towhich the upper surface 45 a of the adhesion layer 45 is exposed, isformed. It is preferable that the insulating layer 46 is formed to coverthe surface 4 a of the trench formation layer 4, and a part of theadhesion layer 45 (for example, an end portion of the upper surface 45 aof the adhesion layer 45).

The insulating layer 46 is formed of a material having insulatingproperties. The material having the insulating properties may be aninorganic material or a resin. Examples of the inorganic materialinclude a compound containing silicon, such as SiO₂ and SiN. Examples ofthe resin include an epoxy resin, polyimide, and the like.

As illustrated in FIG. 6D, a UBM layer (under-barrier metal layer) 47 isformed on the upper surface 45 a of the adhesion layer 45, which isexposed into the opening portion of the insulating layer 46. It ispreferable that the UBM layer 47 is formed according to an electrolessplating method of growing the metal plating from the adhesion layer 45.The UBM layer 47 may contain at least type of metal selected from thegroup consisting of nickel, cobalt, iron, and copper. The UBM layer 47may further contain a non-metal element such as phosphorus. It ispreferable that the UBM layer 47 contains nickel, or contains nickel andphosphorus.

As illustrated in FIG. 6E, the connection portion 44 is formed on asurface 47 a of the UBM layer 47 on a side opposite to theelectroconductive substrate 1A. A configuration material and a formingmethod of the connection portion 44 may be identical to theconfiguration material and the forming method of the embodimentdescribed above, and in this modification example, it is preferable thatthe connection portion 44 is formed according to an electroless platingmethod of growing the metal plating from the UBM layer 47, from theviewpoint of mounting a smaller light emitting element 40. It ispreferable that the connection portion 44 contains tin or an alloythereof, as a configuration material. A part of the connection portion44 to be formed on the UBM layer 47, may be in contact with a surface ofthe insulating layer 46.

As illustrated in FIG. 6F, the light emitting element 40 is connected tothe formed connection portion 44. Accordingly, it is possible to obtaina display device 50C in which the light emitting element 40 is connectedto the electroconductive pattern layer 8 of the electroconductivesubstrate 1A through the connection portion 44, the UBM layer 47, andthe adhesion layer 45. That is, the light emitting element 40 is mountedon the electroconductive substrate 1A, according to the step includingforming the adhesion layer 45, the insulating layer 46, the UBM layer47, and the connection portion 44, and connecting the light emittingelement 40 to the connection portion 44.

FIG. 7 is a plan view schematically illustrating a main part of adisplay device 50 (50A to 50C) which is obtained according to the methodillustrated in FIGS. 4A to 6F. In the display device 5 illustrated inFIG. 7, a plurality of light emitting elements 40 (40 a, 40 b, and 40 c)are arranged along an extending direction L of two adjacent linearportions while straddling two adjacent linear portions 81 and 82 of theelectroconductive pattern layer 8 of the electroconductive substrate 1A.The light emitting element 40 may be configured of a light emittingelement 40 a including a red light emitting unit, a light emittingelement 40 b including a green light emitting unit, and a light emittingelement 40 c including a blue light emitting unit, and such lightemitting elements 40 a, 40 b, and 40 c may be arranged in an arbitraryorder. For example, a distance D₁ in a width direction of theelectroconductive pattern layer 8 may be less than or equal to 400 μm,and a distance D₂ in the extending direction L of the electroconductivepattern layer 8 may be less than or equal to 200 μm, as a distancebetween the adjacent light emitting elements 40 (40 a, 40 b, and 40 c).

In the method of producing the display device 50 described above, a stepof disposing a sealing portion covering an exposed portion of the lightemitting element 40, may be further provided. The sealing portion, forexample, may be formed of a resin such as a silicone resin, an epoxyresin, and an olefin resin.

It is also possible to mount the light emitting element on theelectroconductive substrate 1B which is produced by the method accordingto the second embodiment, according to the same method as that of thefirst embodiment, and to produce the display device.

[Electronic Device]

In another embodiment, an electronic component other than the lightemitting element can be mounted on the electroconductive substrate whichis produced by the method described above. Examples of the electroniccomponent other than the light emitting element, include a passivecomponent such as a capacitor, an inductor, and a thermistor, asemiconductor element, a connector, and the like. Accordingly, it ispossible to produce an electronic device including an electroniccomponent on the electroconductive substrate which is produced by themethod described above, in addition to the display device.

EXAMPLES

Hereinafter, the present invention will be specifically described byexamples, but the present invention is not limited to the examples.

Example 1

A catalyst-containing resin for forming a foundation layer forming,containing 20 mass % of Pd particles, and an isocyanate resin, wasprepared. The catalyst-containing resin was applied onto a PET film (athickness of 100 μm), which is a transparent base material, by using abar coater. The coated film was heated at 80° C., and was cured, andthus, the foundation layer (a thickness of 100 nm) was formed. Afterthat, an ultraviolet ray curable transparent acryl-based oligomer wasapplied onto the foundation layer, by using a bar coater, and thus, atrench formation layer (a thickness of 2 μm) was formed.

An Ni mold in which a mesh-like pattern was formed and a convex portionhaving a width of 1 μm was provided, was prepared. The mold was pressedagainst the trench formation layer, and a tip end of the convex portionof the mold reached the foundation layer. In such a state, the trenchformation layer was cured by being irradiated with an ultraviolet ray.Accordingly, a trench including a bottom surface to which the foundationlayer was exposed, was formed. The width of the trench was 1 μm, thedepth of the trench was 2 μm, and a distance between adjacent trencheswas 100 μm.

A laminated body including the trench formation layer in which thetrench was formed, was dipped in an alkaline degreasing liquidcontaining a surfactant, for 5 minutes. After that, the laminated bodytaken out from the degreasing liquid, was washed with pure water. Thelaminated body after being washed, was dipped in an electroless platingliquid containing nickel sulfate and sodium hypophosphite, for 3minutes, and metal plating as a seed layer (a thickness of 100 nm)formed of Ni and P, was grown from the foundation layer which wasexposed to the bottom surface of the trench. The laminated body takenout from the electroless plating liquid, was washed with pure water.Subsequently, the laminated body in which the seed layer was formed, wasdipped in an aqueous solution containing Pd, for 5 minutes, and then,was washed with pure water, and the Pd particles as a catalyst wereadsorbed in the seed layer. After that, the laminated body was dipped inan electroless plating liquid containing copper sulfate and formalin,for 5 minutes, and thus, Cu plating (an upper metal plating layer)filling the trench, was grown on the seed layer. The laminated bodytaken out from the electroless plating liquid, was washed with purewater, and was dried at 80° C. for 3 minutes, and a mesh-like patternwas formed, and thus, an electroconductive substrate including anelectroconductive pattern layer formed of the seed layer and the Cuplating, was obtained. In the electroconductive substrate, a width W ofthe electroconductive pattern layer was 1 μm, the thickness of theelectroconductive pattern layer was 2 μm, and an aspect ratio(Thickness/Width) of the electroconductive pattern layer was 2. Adistance S between adjacent electroconductive pattern layers was 200 μm.In the obtained electroconductive substrate, a sectional surface of theelectroconductive pattern layer was cut out by using a cross-sectionpolisher, and it was confirmed that a gap was formed between a lateralsurface of the trench and a lateral surface of the electroconductivepattern layer, according to observation using an electron scanningmicroscope.

Examples 2 to 5

An electroconductive substrate was prepared by the same method as thatin Example 1, except that the width W of the electroconductive patternlayer (the width of the trench) and the thickness of theelectroconductive pattern layer (the depth of the trench) was changed tothe values shown in Table 1.

Examples 6 to 9

An electroconductive substrate was prepared by the same method as thatin Example 1, except that the thickness of the electroconductive patternlayer (the depth of the trench) was changed to the values shown in Table1.

Comparative Example 1

An electroconductive substrate not including the foundation layer, wasprepared according to a production method of the related art illustratedin FIGS. 8A to 8D. First, an ultraviolet ray curable transparentacryl-based oligomer was applied onto the same PET film (the basematerial 2) as that of the examples, and the trench formation layer 4 (athickness of 2 μm) was formed. A mold in which a mesh-like pattern wasformed and a convex portion having a width of 1 μm was provided, waspressed against the trench formation layer 4, and a tip end of theconvex portion reached the base material 2. In such a state, the trenchformation layer 4 was cured by being irradiated with an ultraviolet ray,and thus, a laminated body 5C was obtained in which the trench 6including the bottom surface to which the base material 2 was exposed,was formed (FIG. 8A). Next, a seed layer 11 formed of Cu, covering theentire surface 4 a of the trench formation layer 4 and the entire bottomsurface 6 a, was formed by a sputtering method (FIG. 8B). After that,the laminated body 5C was dipped in an electroless plating liquidcontaining copper sulfate and formalin, and thus, Cu plating was grownfrom the seed layer 11, and a Cu plating layer 8A which filled thetrench 6 and covered the entire trench formation layer 4, was formed(FIG. 8C). After that, a portion of the Cu plating layer 8A, other thana portion filling the inside of the trench 6, was removed by etching(FIG. 8D), and thus, an electroconductive substrate 1C according toComparative Example 1, including the electroconductive pattern layer 8,was prepared. In the obtained electroconductive substrate, the sectionalsurface of the electroconductive pattern layer was cut out by using across-section polisher, and it was confirmed that the electroconductivepattern layer 8 adhered to the lateral surfaces 6 b and 6 c of thetrench 6, and a gap was not formed therebetween, according toobservation using an electron scanning microscope.

<Bending Test>

A sample of each electroconductive substrate having a length of 150 mmand a width of 50 mm, was prepared. The sample was subjected to abending test according to JISC5016, using a bending resistance testingmachine illustrated in FIG. 9. That is, the electroconductive substrate1 was set to conform to a circular circumferential surface (CurvatureRadius d: 5 mm) of a bent portion 14 while fixing an end portion 12 ofthe electroconductive substrate 1 to a fixation portion 13, and thus,the electroconductive substrate 1 was disposed to be bent. After that,an end portion 15 on a side opposite to the end portion 12 was movedback and forth along a direction illustrated by an arrow B. A movementdistance that the end portion 15 was moved back and forth, was set to 30mm, and a back and forth cycle was set to 150 times/minute, and thus,the end portion 15 was repeatedly moved back and forth for 1 minute.

<Evaluation of Electroconductivity (Measurement of Surface Resistance)>

Surface resistance of each of the electroconductive substrates beforeand after the bending test was measured by using a non-contact typeresistance measuring instrument EC-80P (manufactured by NAPSONCORPORATION). The measurement was performed in a region of ϕ20 mm of asurface of the electroconductive substrate. Electroconductivity wasevaluated in the following four ranks, on the basis of the measurementresult. A rank A indicates that the electroconductivity is mostexcellent.Rank A: The surface resistance is less than 5Ω/squareRank B: The surface resistance is greater than or equal to 5 Ω/squareand less than 10Ω/squareRank C: The surface resistance is greater than or equal to 10 Ω/squareand less than 15Ω/squareRank D: The surface resistance is greater than or equal to 15 Ω/square

<Evaluation of Adhesiveness>

A sectional surface of the electroconductive substrate after the bendingtest, was observed with an electron scanning microscope, and thepresence or absence of the peeling of the electroconductive patternlayer from the foundation layer or the base material was confirmed.

<Evaluation of Transparency>

A total light transmittance of the electroconductive substrate wasmeasured according to JISK7136, using a haze meter NDH5000 (manufacturedby NIPPON DENSHOKU INDUSTRIES CO., LTD.). The transparency of thetransparent electroconductive substrate was evaluated in the followingthree ranks, with respect to the measurement result. A rank A indicatesthat the transparency is most excellent.Rank A: Total Light Transmittance of Electroconductive Substrate/TotalLight Transmittance of Base Material×100=greater than or equal to 98%Rank B: Total Light Transmittance of Electroconductive Substrate/TotalLight Transmittance of Base Material×100=greater than or equal to 96%and less than 98%Rank C: Total Light Transmittance of Electroconductive Substrate/TotalLight Transmittance of Base Material×100=less than 96%

TABLE 1 Electroconductive pattern layer Evaluation result (trench) Afterbending test W/S Thickness Aspect Presence of Peeling (μm) (μm) ratioabsence of gap Transparency Electroconductivity (adhesiveness)Electroconductivity Example 1 1/200 2 2 Present B B Absent B Example 20.3/200  0.6 2 Present A C Absent C Example 3 0.5/200  1 2 Present A BAbsent B Example 4 3/200 6 2 Present B A Absent A Example 5 3.5/200  7 2Present C A Absent A Example 6 1/200 4.5 4.5 Present C A Absent AExample 7 1/200 4 4 Present B A Absent A Example 8 1/200 1 1 Present B BAbsent B Example 9 1/200 0.5 0.5 Present A B Absent C Comparative 1/2002 2 Absent B B Present D Example 1

As shown in Table 1, in the electroconductive substrates of Examples 1to 9, it was found that the electroconductive pattern layer after thebending test was prevented from being peeled off, and excellentelectroconductivity was maintained.

Examples 10 to 12

A plurality of electroconductive substrates were prepared by the samemethod as that in Example 1. Such electroconductive substrates weredipped in an aqueous solution containing Pd, for 5 minutes, and then,were washed with pure water, and thus, the Pd particles as the catalystwere adsorbed in the surface of the electroconductive pattern layer.After that, the electroconductive substrate was dipped in an electrolessplating liquid for black Ni plating, for 3 minutes, and thus, a black Niplating film was formed as the uppermost layer of the electroconductivepattern layer on a side opposite to the bottom surface of the trench andthe lateral surface side of the trench. Each of the electroconductivesubstrates taken out from the electroless plating liquid, was washedwith pure water. Further, the black Ni plating film was subjected to anacid treatment, surface roughness Ra of the black Ni plating film wasadjusted to be 15 nm (Example 10), 58 nm (Example 11, or 65 nm (Example12), by adjusting the time of the acid treatment. Ra was measured in avisual field of 1 μm, by using a scanning probe microscope. Ra of theelectroconductive pattern layer of Example 1 was 8 nm.

<Evaluation of Electroconductivity and Measurement of Transmittance>

In the electroconductive substrates of Examples 10 to 12 and Example 1,the transparency and the electroconductivity were evaluated by the samemethod as the method described above. As shown in Table 2, it was foundthat when Ra was 15 nm to 60 nm, the transparency and theelectroconductivity were particularly excellent.

TABLE 2 Electroconductive pattern layer (trench) Evaluation result W/SThickness Ra Electro- (μm) (μm) (nm) Transparency conductivity Example 11/200 2 8 B B Example 10 1/200 2 15 A B Example 11 1/200 2 58 A BExample 12 1/200 2 65 A C

Examples 13 to 15

A plurality of electroconductive substrates were prepared by the samemethod as that in Example 1. A curable resin composition for forming aprotective film was applied onto the surface of the trench formationlayer and the electroconductive pattern layer of such electroconductivesubstrates, with a doctor blade. The coated film was dried, and then,was cured by being irradiated with an ultraviolet ray, and thus, theprotective film (a thickness of 100 nm) covering trench formation layerand the electroconductive pattern, was formed. The curable resincomposition for forming the protective film, used here, contains afiller (silicon oxide) and a fluorine resin. A refractive index of theprotective film was adjusted to be the values shown in Table 3 bychanging the content of the filler.

<Evaluation of Transparency>

In the electroconductive substrates of Examples 13 to 15 and Example 1,the transparency of the electroconductive substrate was measured by thesame method as the method described above. The results are shown inTable 3. As shown in Table 3, it was found that in a case where therefractive index of the protective film was greater than a refractiveindex of the air of 1.0, and was less than the refractive index of thetrench formation layer, the transparency was particularly excellent.

TABLE 3 Electroconductive pattern layer (trench formation layer)Protective film Refractive Content of W/S Thickness index of trenchfiller Refractive Evaluation result (μm) (μm) formation layer (mass %)index Transparency Example 1 1/200 2 1.51 — (1.0) B Example 13 1/200 21.51 82 1.33 A Example 14 1/200 2 1.51 25 1.50 B Example 15 1/200 2 1.516 1.55 C

According to the present invention, it is possible to produce theelectroconductive substrate in which the electroconductive pattern layerfilling the trench is provided, and the peeling of the electroconductivepattern layer and a decrease in the electroconductivity due to bendingare suppressed. The method of the present invention is excellent,compared to a method including removing the electroconductive layer byetching, since the electroconductive pattern layer easily have ameasurably large thickness, and thus, excellent electroconductivity iseasily obtained.

Further, the present invention is also capable of providing the methodof producing the electronic device or the display device in which theelectroconductive pattern layer of the electroconductive substrate isprevented from being peeled off. In particular, in the display device,recently, a display device including a light emitting element such as alight emitting diode (LED) (for example, an LED display) has developed.In a liquid crystal display (LCD), backlight is controlled bytransmissive liquid crystals, but in the LED display, a pixel isconfigured by using a light emitting diode which is a natural lightemitting element. Accordingly, the LED display has characteristics suchas a high brightness, long lifetime, and a high viewing angle.

In the display device including the light emitting element, it ispreferable to decrease the size of the light emitting element itself, inorder to improve the resolution. However, in a case where the size ofthe light emitting element decreases, it is necessary to form a fineelectroconductive pattern layer, and thus, there is a tendency that theelectroconductive pattern layer is easily peeled off, and theelectroconductivity is difficult to be ensured. According to the presentinvention, it is possible to easily producing the display device inwhich even in a case where the size of the light emitting elementdecreases, the electroconductive pattern layer of the electroconductivesubstrate is hardly peeled off, and adhesiveness between the lightemitting element and the electroconductive substrate is excellent.

1, 1A, 1B: electroconductive substrate, 2: base material, 3: foundationlayer, 6: trench, 6 a: bottom surface of trench, 6 b, 6 c: lateralsurface of trench, 8: electroconductive pattern layer, 40: lightemitting element, 44: connection portion, 45: adhesion layer, 46:insulating layer, 47: UBM layer, 50: display device.

What is claimed is:
 1. A method of producing an electroconductive substrate including a base material, and an electroconductive pattern layer disposed on one main surface side of the base material, the method comprising: a step of forming a trench including a bottom surface to which a foundation layer is exposed, and a lateral surface which includes a surface of a trench formation layer according to an imprint method including pushing a mold including a convex portion into the trench formation layer formed on the foundation layer which is formed on the base material; a step of adsorbing a catalyst on the foundation layer which is exposed to the bottom surface of the trench; and a step of forming the electroconductive pattern layer which includes metal plating and fills the trench, by growing the metal plating from the foundation layer on which the catalyst is adsorbed.
 2. The method according to claim 1, wherein the metal plating is grown such that a gap is formed between at least a part of a lateral surface of the electroconductive pattern layer and the lateral surface of the trench.
 3. The method according to claim 1, further comprising: a step of blackening a surface of the electroconductive pattern layer, the surface including a surface on a side opposite to the bottom surface of the trench.
 4. The method according to claim 1, further comprising: a step of forming a protective film covering at least a part of a surface of the trench formation layer and the electroconductive pattern layer on a side opposite to the base material.
 5. The method according to claim 1, wherein the electroconductive pattern layer forms a mesh-like pattern.
 6. A method of producing an electronic device including an electroconductive substrate which includes a base material, and an electroconductive pattern layer disposed on one main surface side of the base material, and an electronic component, the method comprising: a step of forming a trench including a bottom surface to which a foundation layer is exposed, and a lateral surface which includes a surface of a trench formation layer according to an imprint method including pushing a mold including a convex portion into the trench formation layer formed on the foundation layer which is formed on the base material; a step of adsorbing a catalyst on the foundation layer which is exposed to the bottom surface of the trench; a step of forming the electroconductive pattern layer which includes metal plating and fills the trench, by growing the metal plating from the foundation layer on which the catalyst is adsorbed; and a step of mounting the electronic component on the electroconductive substrate including the base material and the electroconductive pattern layer.
 7. The method according to claim 6, wherein the step of mounting the electronic component on the electroconductive substrate, includes forming a connection portion on the electroconductive pattern layer, and connecting the electronic component to the electroconductive pattern layer through the connection portion.
 8. The method according to claim 6, wherein the step of mounting the electronic component on the electroconductive substrate, includes forming an adhesion layer on the electroconductive pattern layer, forming an insulating layer which covers a surface of the trench formation layer on a side opposite to the foundation layer, and includes an opening portion to which a part of the adhesion layer is exposed, forming a UBM layer on a surface of the adhesion layer which is exposed into the opening portion of the adhesion layer, forming a connection portion on the UBM layer, and connecting the electronic component to the electroconductive pattern layer through the connection portion, the UBM layer, and the adhesion layer.
 9. The method according to claim 6, wherein the metal plating is grown such that a gap is formed between at least a part of a lateral surface of the electroconductive pattern layer and the lateral surface of the trench.
 10. A method of producing a display device including an electroconductive substrate which includes a base material, and an electroconductive pattern layer disposed on one main surface side of the base material, and a light emitting element, the method comprising: a step of forming a trench including a bottom surface to which a foundation layer is exposed, and a lateral surface which includes a surface of a trench formation layer according to an imprint method including pushing a mold including a convex portion into the trench formation layer formed on the foundation layer which is formed on the base material; a step of adsorbing a catalyst on the foundation layer which is exposed to the bottom surface of the trench; a step of forming the electroconductive pattern layer which includes metal plating and fills the trench, by growing the metal plating from the foundation layer on which the catalyst is adsorbed; and a step of mounting the light emitting element on the electroconductive substrate including the base material and the electroconductive pattern layer.
 11. The method according to claim 10, wherein the step of mounting the light emitting element on the electroconductive substrate, includes forming a connection portion on the electroconductive pattern layer, and connecting the light emitting element to the electroconductive pattern layer through the connection portion.
 12. The method according to claim 10, wherein the step of mounting the light emitting element on the electroconductive substrate, includes forming an adhesion layer on the electroconductive pattern layer, forming an insulating layer which covers a surface of the trench formation layer on a side opposite to the foundation layer, and includes an opening portion to which a part of the adhesion layer is exposed, forming a UBM layer on a surface of the adhesion layer which is exposed into the opening portion of the adhesion layer, forming a connection portion on the UBM layer, and connecting the light emitting element to the electroconductive pattern layer through the connection portion, the UBM layer, and the adhesion layer.
 13. The method according to claim 10, wherein the metal plating is grown such that a gap is formed between at least a part of a lateral surface of the electroconductive pattern layer and the lateral surface of the trench. 